Mozilla has just opened the doors to their Mozilla Marketplace, where you can download web apps and games, at a limited capacity as the service is in an experimental stage. But, it steps outside of the boundaries of the usual digital download storefronts like Google's Chrome Web Store.
Mozilla Marketplace lets you download something from the store, and the app gets treated like an actual desktop app. This means they are independent of the browser, so Windows users can access them from the Start Menu, and even uninstall an app traditionally through the Control Panel.
If you want to try the Mozilla Marketplace out, you'll need to download and install the Nightly build of Firefox 16, as functionality for the store isn't available through the public release yet. At the moment, there are 200 apps available on the store, with most of them being free. As time goes on, this number should grow exponentially. Click here to try it out!